I've worked with various video editing software for many years, though I'm no where near an expert. I know since H.265 technology came in it become easier to compress a file to less than half the size of a H.264 file without losing quality.

I've seen a few examples over the last year. A 21 minute file using H.265 at 1080p is around 315MB. The same file using H.264 is 1.4GB.

I've noticed people using H.265 tend to only encode in 1080p or 720p. People still using the H.264 will use 1080p, 720p and 480p.

I think H.265 is within reach of 4K through some manipulations.

I just hope the technology we have can be updated to be able to use H.266 faster than it took devices to catch up to using H265.

As always it's about fast enough processors to decode the stuff in real time, however with the advent of GPGPUs and nVidia pushing out some quite tasty mobile chips with the Tegra X2 coming soon hopefully the combination of raw power and the additional instructions to accelerate decoding will mean software and firmware upgrades will suffice by the time the standard is ready.

NBC still uses flash, sky silverlight. Whilst both those can work with h.265 it shows how often they review and update their streaming platform.

Netflix I expect to be the first to adopt out of the big players.

They also have to consider what benefits the most users, lots of older hardware doesnt accelerate h.265 but does h.264 so if 265 was rolled out they would need some kind of way to detect if older hardware is in use and then fall back to 264. If they did that of course it also would mean all content would need 2 copies. So not a simple matter.

Google are favouring their own propriety type solution VP9, which isnt supported by many operating systems regardless of hardware. I had to install an addon to force h.264 to be used instead for better cpu utilisation.

The Alliance for Open Media (founding members Amazon, Cisco, Google, Intel Corporation, Microsoft, Mozilla, and Netflix) are working on the new royalty free codec AV1. Still early days it seems though.